Python FOR LOOPS

What the fuck is with Python's for loops.

What's the difference between:

for i in list[0]:

for i in list[0:]:

for i in list[:0]:

>>1
The first one runs the for loop once, with i set to list[0], the second one runs the loop for each element of list, and the third one does nothing.

To see why, enter list[0], list[0:] and list[:0] in the interpreter.